The present invention refers to optical detection systems for motor-vehicles, of the type able for detecting the condition of the road surface on which the vehicle is travelling in such a manner to distinguish, for example, between a dry, wet, snow-covered or ice-covered surface.
In particular, the invention regards a system of this type comprising:                a photodetector unit mounted on board the motor-vehicle, for receiving the electromagnetic radiation diffused by the road surface, and        a control and processing electronic unit, suitable for receiving signals output from said photodetector unit and processing them with the aim of determining the condition of the road surface.        
This type of detection system, which employs an emitter unit for lighting the road surface to be detected, was proposed in the European patent application EP 08 425 784.9 of the same Applicant, filed on Sep. 12, 2008 and still not open to public inspection as of date of filing of the present application.